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MM: Fachverband Metall- und Materialphysik
MM 18: Poster Session I
MM 18.20: Poster
Montag, 16. März 2020, 18:15–20:00, P4
Impact of magnetism on the energy of stacking faults in the C14 NbFe2 Laves phase — •Ali Zendegani, Fritz Körmann, Tilmann Hickel, and Jörg Neugebauer — Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany
The stacking fault energy (SFE) is a key descriptor for predicting plastic deformation mechanisms of materials. In Laves phases basal synchroshear-formed stacking faults (BSSF), which locally transform the hexagonal C14 into the cubic C15 Laves phase, support the propagation of dislocations. The calculation of the BSSF in NbFe2, however, results in a negative energy, if a ferrimagnetic ground state configuration is used for the ab initio supercell. The underlying reason is that ferrimagnetic C15 is more stable than ferrimagnetic C14 in this system [1].
Considering the very low magnetic ordering temperature of 10 K we, therefore, performed computationally challenging paramagnetic calculations. In this case C14 has the lower energy as compared to C15. A transfer of this method to the more complex BSSF containing supercells is not yet feasible. Instead, we present an alternative analytical approach [2], which correlates the SFE with the difference of the C14 and C15 bulk energies and thus allows to determine the energy of the complex BSSF in NbFe2 properly including the magnetic contribution [1].
[1] M. Šlapáková, et al. Acta Materialia 183 (2020):362-376.
[2] F. Chu, et al. Philosophical magazine letters 72.3 (1995): 147-153.